1. Field of the Invention
The present invention relates generally to high-speed aircraft, and more particularly to long range supersonic cruise aircraft having sonic boom shock suppression capabilities.
2. Description of Related Art
Various techniques for reducing sonic boom by suppressing shock waves formed on or around high speed aircraft have been tried for years.
U.S. Pat. No. 5,289,995 to Greene teaches the incorporation of an internal passageway, an articulated intake structure and an articulated exhaust structure which is connected to the intake structure by the passageway. The cross-section of which is essentially the aircraft""s fuselage and engine inlet combined, which helps cancel shocks from the fuselage and engine(s).
U.S. Pat. No. 4,582,276 to Gerhardt teaches incorporating a U-shaped aerodynamic structure into the design of a supersonic aircraft, with the U-shaped structure enabling cancellation of shock waves by expansion waves generated by the apices of the triangularly shaped legs of the U-shaped structure.
U.S. Pat. No. 5,740,984 to Morgenstern teaches altering the direction and shape of the shock wave by using a control device, located at or near the nose section of the aircraft, that has a control surface that can be moved between a retracted position wherein drag on the aircraft is reduced, and an extended position wherein air pressure at the nose section is increased to alter the shape of the shock wave created by the aircraft and hence the sonic boom that impacts the ground.
U.S. Pat. No. 4,114,836 to Graham et al. discloses an aircraft having plural passageways, each having its longitudinal axis substantially parallel to the flight path of the aircraft. The passageways extend through the wings, the fuselage, the horizontal elevators and the rudder for the purpose of permitting air to pass through these areas, thereby reducing drag and sonic boom.
U.S. Pat. No. 4,436,261 to Koleff discloses a sonic boom concentrator for a V/STOL aircraft in the form of a fin having curved sidewalls and truncated ends.
U.S. Pat. No. 5,518,204 to Tracy discloses a supersonic flight aircraft having a longitudinal body and a laterally extending wing, in which laminar airflow conditions are maintained over the leading edge and adjacent the surface of the wing.
As a rule, the foregoing techniques can be categorized as shock cancellation, area/lift distribution tailoring, shock directionality alteration, and slotted edges. Each technique enables sonic boom control and/or wave drag reduction. However, each concept independently has limitations that preclude the development of a feasible xe2x80x9cshock freexe2x80x9d vehicle.
In addition to the published patents, the issue of reducing drag and sonic boom associated with supersonic aircraft has been the subject of research at certain, universities. One such program by George and Seebass"" involved tho theory for tailoring the area and lift distribution verses length to monimize the sonic boom shock strength at the ground. Another such program involves the development of a two-dimensional shock canceling model proposed by Busemann in 1935, as illustrated in FIG. 1. Finally, George examined redirecting boom laterally and showed how to calculate a directionally altered boom reduction underneath a vehicle that persists into the far-field.
The foregoing techniques can be categorized as Artificially Blunted Leading Edge (ABLE), area/lift distribution tailoring, shock cancellation and shock directionality alteration. Each technique enables sonic boom control and/or wave drag reduction. However, each concept independently has limitations that preclude the development of a feasible xe2x80x9cLow Sonic Boomxe2x80x9d vehicle.
Against this background of known technology, the inventors have discovered that by combining techniques, the shortcomings of each can be compensated for or overcome by the benefits of others.
It is therefore an object of the present invention to provide a novel xe2x80x9cLow Sonic Boomxe2x80x9d high speed aircraft, utilizing various body portion orientations such as lifting bodies, flying wings, blended wings along with other such orientations as illustrated in FIGS. 4, 11a, 11b and 12a, 12b, 12c and 12d, by incorporating many of the synergistic passive shock reduction and cancellation devices or techniques, while overcoming many of the disadvantages and drawbacks associated with such devices or techniques.
Another object of the present invention is to suppress sonic boom in a high speed aircraft capable of supersonic flight by incorporating shock cancellation surface configurations around engine nacelles, as illustrated in FIGS. 8 and 9, shaping the aircraft fuselage to provide shock directionality, incorporating slotted edges in the wing, body or canard of the aircraft and designing the area and lift distribution to tailor the ground shock strength and to reduce wave drag of the aircraft.